Important documents such as gold notes/deeds often have printed images thereon that will appear as different ones when copied by a general color copying machine to thereby check the accurate copying of the original images. Such image is referred to as a “reproduction checking image”. It is known that such reproduction checking image is composed of a vanishing or discoloring image (hereinafter described simply as “vanishing image”) that will vanish or discolor when copied by the copying machine and a remaining copyable image. By combining a vanishing image and a remaining image, a reproduction checking image on an original document that causes its invisible characters/figures to appear on a reproduction or a reproduction checking image on a document in which visible characters/figures will vanish after copied can be created. Since a document with such a reproduction checking image thereon provides a reproduction obviously different from the original when copied, it is expected that illegal copying can be checked.
A document with such a reproduction checking image thereon has been produced by printing various matters on a sheet of paper on which the reproduction checking image is printed beforehand. Recently, a user can create and print with a page printer a desired reproduction checking image on a sheet of plain paper. In addition, a copied image can be printed in color since color printers have diffused and provided high resolution.
Even when a reproduction checking image is printed in color, however, a reproduction checking image, which has been printed in a monochromatic manner, is only printed in a single color other than black, and has produced only a visual different effect due to on a part of the reproduction checking image being not copied. Therefore, there is an increasing need for reproduction checking images that produce new visual different effects using a combination of various colors.
It is an object of the present invention to provide a print control apparatus capable of printing a color reproduction checking image that produces a visual different effect, using a combination of various colors.